1. Field of the Invention
This invention relates to a valve packing removal tool. More specifically, the invention relates to a packing removal tool in which the downward and rotary movement of the valve stem is used to propel downward and rotate the removal blade.
2. Description of Related Art
In the prior art there are examples of packing extractors. One is shown in the U.S. Pat. No. 3,651,717 to W. P. Johnston, Jr. In this arrangement a split ring is held on the valve stem by a split nut. The ring, free to rotate, is engageable by a spanner wrench and has a downward helix, winding about the valve stem and ending in an extractor point. In operation, the Johnston tool is installed on the valve stem or pump shaft so that the point touches the packing to be extracted. As the ring is turned by the spanner, the point digs into the packing and extracts it.
Other art includes U.S. Pat. No. 4,611,510 to Morton in which a hinged cylindrical tool can be installed on the pipe and is provided with a turning rod, the cylindrical tool having forwardly projected piercing edges which dig into the packing as the cylindrical body is turned.
U.S. Pat. No. 2,822,713 to Schmidt discloses a core tool which slips over a valve stem and may be turned to remove the packing as the points dig in.
U.S. Pat. No. 1,635,743 to Davenport shows a hinged structure which may encircle a piston rod and may be turned to dig into the packing and may be pulled up by a lever.
U.S. Pat. No. 4,509,392 to Smith shows a spreader-type tool which may have its jaws inserted between the packing and the projection and spread to force the cutter into the packing to remove it.
The above art relies on brute force of the operator to lower the actual extractor blade, and there is no means for precisely controlling the travel of the extractor blade. It is an object of the present invention to use the valve stem adjacent the packing as the means by which the extractor blade is driven downward. Hence, during the downward movement there is no need for additional wrenches, rods, or other means to rotate the extractor.
In a preferred embodiment, while the rotary movement may be provided by the valve stem itself, the blade is permitted to "free-wheel" and move down into the packing tool at a rate depending partly on the blade angle. Once the blade arrives at the floor of the packing chamber, the "free-wheeling" assures that no scoring of the floor will occur.